THE SKULL. 51 
crest (c), passes craniad in the middle line across the inter- 
parietal bone: it varies greatly in extent, reaching ina very old 
and muscular cat to the cranial border of the parietals, while 
in kittens it does not exist. The most prominent portions of 
the skull in this region, just craniad of the middle of the parie- 
tal bones, are known as the parietal tubercles or eminences (¢@). 
A faint curved line (¢) runs from the cranial end of the sagittal 
crest craniolaterad to the base of the zygomatic process of the 
frontal: it marks the dorsal boundary of the origin of the tem- 
poral muscle, and may therefore be considered the dorsal 
boundary of the temporal fossa. This fossa extends from its 
dorsal boundary as far laterad and caudad as the lambdoidal 
ridge (a), and as far craniad as a line connecting the tip of the 
zygomatic process of the frontal (/) with the frontal process of 
the malar (2). The temporal muscle takes origin from its 
surface. 
The middle portion of the dorsal surface is formed by the 
frontals (5). Each frontal presents laterally a prominent 
zygomatic process (/), extending ventrolaterad toward a cor- 
responding (frontal) process (4) of the malar bone. These two 
processes mark the boundary between the orbital fossa (craniad) 
and the temporal fossa (caudad). Craniad of the zygomatic 
process of the frontal a sharp margin separates the dorsal sur- 
face of the skull from the wall of the orbital fossa: this is the 
supraorbital arch or margin (2). 
The cranial portion of the dorsal surface is formed by the 
maxillary (8), nasal (7), and premaxillary bones (9). Just 
craniad of the nasals, bounded ventrad and craniad by the 
premaxillaries, appears the large opening of tne nares (¥), 
leading into the nasal cavity. 
The zygomatic arch (.g) is formed by the zygomatic process 
of the temporal (7) and the malar or zygomatic bone (6). 
Each presents near its middle a prominent dorsocaudally 
directed process, the frontal process (4) of the malar bone. The 
zygomatic arch forms the lateral boundary of the temporal and 
orbital fosse, which are separated by a line connecting the 
frontal process of the malar (Z) and the zygomatic process of 
the frontal (/). 
